Claims
- 1. A process for polymerizing ethylene to form a polyethylene homopolymer having a MWD greater than 4 and suitable for forming a film having an MVTR less than 0.3 g mil/100 in2/day, which comprises contacting the ethylene under slurry or gas phase reaction conditions with a chromium-silica cogel catalyst containing titanium, wherein the catalyst contains titanium added in at least two steps: (1) titanium added as part of a first cogel formation, comprising chromium, titanium and silica, and (2) titanium added in a post-titanation step after the first cogel is formed and dried.
- 2. The process in accordance with claim 1 wherein the amount of titanium in the first cogel is between 1 wt. % and 5 wt. % based on the dried first cogel, and the amount of titanium in the post-titanated catalyst is between 5 wt. % and 15 wt. %.
- 3. The process in accordance with claim 1 wherein the amount of titanium in the first cogel is between 1.5 wt. % and 4.0 wt. % based on the dried first cogel, and the amount of titanium in the post-titanated catalyst is between 6 wt. % and 12 wt. %.
- 4. The process in accordance with claim 3 wherein the post-titanated catalyst is calcined at 1200° F. to 1400° F.
- 5. The process in accordance with claim 1 wherein the reaction conditions are slurry.
- 6. The process in accordance with claim 1 wherein the MWD is greater than 6.
- 7. The process in accordance with claim 1 wherein the MVTR is less than 0.25 g·mil/100 in2/day.
Parent Case Info
This application claims the benefit of U.S. Provisional application Ser. No. 60/190,724, filed Mar. 20, 2000.
Foreign Referenced Citations (1)
Number |
Date |
Country |
0 882 740 |
Sep 1998 |
EP |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/190724 |
Mar 2000 |
US |